Object Lifetime - Destroying Objects

Destroying Objects

It is generally the case that after an object is used, it is removed from memory to make room for other programs or objects to take that object's place. In order for this to happen, a destruction method is called upon that object. Destroying an object will cause any references to the object to become invalid.

A destructor is a method called when an instance of a class is deleted, before the memory is deallocated. Note that in C++, a destructor can not be overloaded like a constructor can. It has to have no arguments. A destructor does not need to maintain class invariants.

In garbage collecting languages, objects may be destroyed when they can no longer be reached by the running code. Examples of this are Python and Java. Python has destructors, and they are optional. In many garbage collecting languages, finalizers (which are called before an object is garbage-collected) are used instead of destructors, since the point of garbage-collection is not predictable in these languages. Example of these include Java and Ruby.